If you examine a clutch disc, you will notice that they are not flat.
They are made with the radial fingers twisted.
That is called Marcel. It is intended to act as a spring and to help the disc release from the flywheel.
That twisting from flat contributes to the total clearance needed.
I don't know if the amount of Marcel is a constant with clutch manufacturing or not but it may be that varies as well?
Some racing clutches have no Marcel. That makes them lousy street clutches. No Marcel makes them chatter and they tend to feel like that they are only 100% on or 100% off. Forget about driving those in "traffic".
You should inquire about that feature,i.e., whether it is included or not in the clutch you are considering. When you go to a multi-disc design, it is essentially a racing clutch. Exercise caution there.
This may be getting "into the weeds" but sometimes that's where the answer is.